Allow hiding of additional items

HIDE_AUTHORS is already supported, extend to support hiding
archives, categories and the complete article header banner line.

Signed-off-by: Neil Williams <neil.williams@linaro.org>

alchemy/templates/article.html

@@ -16,6 +16,7 @@
 {% block content %}
   <article class="article">
     <header>
+        {% if not HIDE_BANNER %}
       <ul class="list-inline">
         <li class="list-inline-item text-muted" title="{{ article.date.isoformat() }}">
           <i class="fa fa-clock-o"></i>
@@ -42,6 +43,7 @@
           </li>
         {% endif %}
       </ul>
+      {% endif %}
     </header>
     <div class="content">
       {{ article.content }}

alchemy/templates/include/footer.html

@@ -3,11 +3,15 @@
     {% if not HIDE_AUTHORS %}
       <li class="list-inline-item"><a href="{{ SITEURL }}/authors.html">Authors</a></li>
     {% endif %}
+    {% if not HIDE_ARCHIVES %}
     <li class="list-inline-item"><a href="{{ SITEURL }}/archives.html">Archives</a></li>
+    {% endif %}
+    {% if not HIDE_CATEGORIES %}
     <li class="list-inline-item"><a href="{{ SITEURL }}/categories.html">Categories</a></li>
     {% if tags|length %}
       <li class="list-inline-item"><a href="{{ SITEURL }}/tags.html">Tags</a></li>
     {% endif %}
+    {% endif %}
   </ul>
   <p class="col-sm-6 text-sm-right text-muted">
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